problem with savefig and PS files

/usr/lib/python2.3/site-packages/matplotlib/backends/backend_agg.py

    > in print_figure(self, filename, dpi, facecolor, edgecolor,
    > orientation) 458 svg.print_figure(filename, dpi, facecolor,
    > edgecolor, orientation) 459 elif ext.find('ps')>=0 or
    > ext.find('ep')>=0:
    --> 460 from backend_ps import FigureCanvasPS # lazy import
    > 461 ps = self.switch_backends(FigureCanvasPS) 462
    > ps.print_figure(filename, dpi, facecolor, edgecolor,
    > orientation)

    > ImportError: cannot import name FigureCanvasPS

This looks you might have a bad install. I would remove
site-packages/matplotlib and try re-installing cleanly. If the error
persists, make sure that you don't have a copy of backend_ps.py
anywhere in your PYTHONPATH (do 'locate backend_ps' to find out if
there are any errant copies lying around.).

Your example runs fine on my system.

JDH